Our invention relates to single phase aqueous surfactant-free nontoxic air freshening compositions and wick-containing air freshening devices using such compositions.
Conventional liquid air fresheners generally comprise a reservoir containing a mixture which may be a true solution, a colloidal solution or a microemulsion of a perfume with a solvent into which dips a wick which is connected to an emanating surface. The perfume mixture travels up the wick to the emanating surface from which the perfume evaporates and freshens the surrounding atmosphere. Perfumes used in those air fresheners are generally oils and are therefore generally insoluble in water in the absence of any other agents. Systems in which the perfume solution is aqueous based therefore always contain a surface active agent which solubilizes the perfume in water. The amount of surfactant has to be quite high, for instance, 10-15% or more by weight based on the total composition.
The surfactants used in such compositions are conventional surfactants, generally anionic surfactants such as alkyl benzene sulfonates and lauryl sulfates. Nonionic surfactants have also been used, but they are more expensive and tend to depress the perception of the perfume odor. These surface active agents are all nonvolatile, and they therefore do not evaporate from the emanating surface. The concentration of surfactant in the emanating surface therefore gradually increases, and the presence of surfactant impedes the progress of perfume in the wick and also prevents the perfume emanating as it should.
Most aqueous based systems also contain a cosolvent in addition to the perfume and surfactant. Examples of cosolvents are ethanol and diethylene glycol monoethyl ethers (DEGMEE). Such compositions always contain a surfactant and therefore suffer the same disadvantages as described above.
Some liquid air fresheners contain little or no water and so are free of surfactant. For example, a solution of perfume in DEGMEE having the structure: ##STR1##
and water is stable as a single phase provided the amount of water is low, for example, below 20% when the amount of perfume is about 10% by weight. Since these compositions cannot tolerate high amounts of water, they tend to be expensive.
U.S. Pat. No. 3,945,950 (incorporated by reference herein) describes solid air freshener compositions, which suffer from different problems to the air fresheners comprising liquid compositions with which our invention is concerned. The solid compositions contain perfume, a diethylene glycol monoalkyl ether and a gelling agent, which is a surface active fatty acid soap or metal salt thereof and an inert liquid. Water is sometimes included in the compositions as some or all of the inert liquid, but only in small amounts of 4% by weight.
In U.S. Pat. No. 4,663,081 issued on May 5, 1987 (the specification for which is incorporated by reference herein), it is indicated that diethylene glycol monobutyl ether (DEGMBE) having the structure: ##STR2##
can, when containing dissolved perfume, incorporate a surprisingly large amount of water compared to other glycol ethers and is therefore more cost effective. It is further indicated in U.S. Pat. No. 4,663,081 that the mixture of DEGMBE and water also has very suitable volatility properties and has a beneficial effect on the rate of emanation of the perfume. It is further indicated in U.S. Pat. No. 4,663,081 that the composition containing the DEGMBE generally comprises between 5 and 30% by weight of perfume; usually between 8 and 20% by weight of perfume and often 10% by weight. It is further indicated in U.S. Pat. No. 4,663,081 that the amounts of perfume in compositions containing DEGMBE affect the amount of water that can be mixed into the solution before a phase separation occurs. It is stated that, for example, when the concentration of perfume in the solution is 10% by weight then the maximum amount of water that can be incorporated in a one phase solution is about 55% by weight, and for a perfume solution at 20% concentration, the maximum amount of water is about 40% by weight.
It is further indicated in U.S. Pat. No. 4,663,081 that the perfume may be any of the perfiumes conventionally used in air fresheners and that "the identity of the perfume makes little difference to the behavior of the solvent system. It is further indicated in U.S. Pat. No. 4,663,081:
"Solutions of perfume in various glycol ethers of varying concentration were loaded with water until phase separation occurred. The maximum amounts of water tolerated in systems at various perfume concentrations for the glycol ethers tested is shown in Table 1. PA1 As can be seen from the table DEGMBE can tolerate a far larger amount of water at a specified perfume concentration than any of the other glycol ethers." PA1 (a) butoxy propoxy propanol; or other alkoxylated alkoxy propanol solvent (defined according to one of the structures: ##STR5## PA1 (b) water; PA1 (c) optionally, a minor amount of nonionic surfactant; and PA1 (d) an effective, phase stabilizing amount of a member selected from the group consisting of alkyl sulfate surfactant, alkyl ethoxy sulfate surfactant and mixtures thereof. PA1 (i) 30-70 weight percent water; PA1 (ii) 5-20 weight percent of a fragrance composition wherein at least 60% of its composition consists of one or more substances having a C log.sub.10 P.ltoreq.2.5 and no more than 40% of any of the components of the perfume composition has a C log.sub.10 P in the range of 2.5&lt;C log.sub.10 P.ltoreq.7.5; and PA1 (iii) 30-60 weight percent of a mixture of two glycol ether compounds, one of which is dipropylene glycol monomethyl ether having the structure: ##STR6## PA1 and the other of which is a compound defined according to the structure: ##STR7## PA1 wherein R is n-propyl or n-butyl.
TABLE 1 Maximum amount of water that can be incorporated into the perfume/glycol ether mixtures, before phase separation. GLYCOL % PERFUME IN MIXTURE ETHER 10 20 30 40 50 PGMBE 10 -- -- -- -- DEGMEE 15 10 10 10 -- DEGDME 20 10 -- -- -- TPGMME 20 10 10 -- -- PGMPE 20 10 10 -- -- PGMME 20 10 10 10 -- DPGMME 20 20 10 10 -- PGMEE 30 20 10 10 -- DEGMBE 60 40 20 20 10
For the purposes of the foregoing table and for use throughout the instant application, the following terms are defined: ##STR3##
It is set forth at column 4, lines 15-17 of U.S. Pat. No. 4,663,081:
"As can be seen from the table DEGMBE can tolerate a far larger amount of water at a specified perfume concentration than any of the other glycol ethers."
In view of toxicity problems associated with DEGMBE having the structure: ##STR4##
it has become apparent that a substitute for the system set forth in U.S. Pat. No. 4,663,081 is needed.
It is an object of our invention to provide such substitution means.
PCT Application No. 97/45516 published on Dec. 4, 1997 discloses and claims a phase-stable liquid refreshment and cleaning composition comprising:
However, the PCT Application No. 97/45516 does not teach the problems solved by our invention.